The present invention relates generally to bicycle systems and frame assemblies. In particular, the present invention relates to a bicycle and frame having a chainstay configured to receive a wide tire in close proximity to a crankset.
Prior art bicycle frames traditionally comprise a plurality of tubes, including a head tube, a top tube, a down tube, a seat tube, chainstays and seat stays. A bottom bracket shell connects the seat tube, down tube and chainstays and receives a bottom bracket. The bottom bracket receives a crankset of a drivetrain for rotational movement. The crankset includes a chain ring configured to engage the chain, and transform forces created by the rider during pedaling into power to drive the rear wheel.
The size, shape and orientation of the tubes may influence not only the size and fit of a bicycle, but they also influence the handling characteristics. For example, altering the length of the chainstays has been shown to correspond to an increase or decrease in responsiveness such that comparatively shorter chainstays tend to increase the responsiveness and maneuverability of a bicycle.
Similarly, tire width may also influence the handling characteristics of a bicycle. Mountain bikes designed for traversing unpaved trails traditionally include tires that have a tread pattern including a number of knobs that project from the tire surface. The pattern and the size of the knobs can vary widely depending upon the discipline of mountain biking for which the tires are designed. Wider tires have a greater surface area to contact the terrain, which tends to provide more stability in comparison with a narrower tire.
While wider tires and shorter chainstays tend to improve traction and handling characteristics, the rear wheel of bicycles must exhibit a minimum amount of clearance between the wheel and all portions of the frame in order to meet safety standards such as CEN 14781 Section 4.10. Consequently, the length of chainstays, the maximum width of tires and the size of chain rings are limited in order to meet safety standards and to prevent the chain ring from interfering with the drive-side chainstay.